Just how is Discover Weekly so good at finding awesome music? Tech Insider talked to the Spotify employee behind the playlist to find out.

"How can we make something for you that feels like a mixtape?"

That's the question Spotify's Matt Ogle asked when he set out with his Product team to create Discover Weekly. While Spotify does have human music experts making thousands of playlists, Ogle quickly realized that the company couldn't employ enough people to make personalized Discover Weekly playlists for millions of people.

So Ogle decided to use algorithms to detect what songs Spotify users are playing "around" each other.

"We look at what you've been listening to," Ogle told Tech Insider. "And what are the songs playing around these songs that you've been jamming on but that we know you haven't heard yet on Spotify."

We're trying to find the missing tracks

Let's say you've been playing a song by The Killers and a song by Bruce Springsteen a lot. Algorithms look for how those songs are played and ordered in other Spotify users' playlists.

If it turns out that, when people play those songs together in their playlists, there's another song sandwiched between them that you've never heard before, that song will show up in your Discover Weekly.

"We're trying to find the missing tracks," Ogle says.

Matt Ogle, the guy at Spotify in charge of Discover Weekly. Alex Heath / Tech Insider Each Discover Weekly intentionally has a mix of new tracks and songs you've already heard.

"Discovery can feel like work, and we wanted to feel very human and natural like the selections that are powering it," Ogle said. Familiar songs will often be guilty pleasures, which is part of the fun, he admits.

I guess that explains why my Discover Weekly includes "Ignition" by R. Kelly.

"Having a little bit of familiarity is key to building trust," Ogle explained. "It can be exhausting to just listen to stuff you've never heard of before."

Ogle and his team are going to keep experimenting with how Discover Weekly finds music, but for now, the experimental playlist is already proving that Spotify can deliver a highly customized listening experience on a massive scale.

"I see Discover Weekly as one of the first products from this new era of personalization [in Spotify]," Ogle said. "But ultimately we'd love for everything you interact with on Spotify to feel like there's a bit of you in it."